.TH std::cos(std::complex) 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::cos(std::complex) \- std::cos(std::complex)

.SH Synopsis
   Defined in header <complex>
   template< class T >
   complex<T> cos( const complex<T>& z );

   Computes complex cosine of a complex value z.

.SH Parameters

   z - complex value

.SH Return value

   If no errors occur, the complex cosine of z is returned.

   Errors and special cases are handled as if the operation is implemented by
   std::cosh(i * z), where i is the imaginary unit.

.SH Notes

   The cosine is an entire function on the complex plane, and has no branch cuts.

   Mathematical definition of the cosine is cos z =

   eiz
   +e-iz
   2

   .

.SH Example


// Run this code

 #include <cmath>
 #include <complex>
 #include <iostream>

 int main()
 {
     std::cout << std::fixed;
     std::complex<double> z(1.0, 0.0); // behaves like real cosine along the real line
     std::cout << "cos" << z << " = " << std::cos(z)
               << " ( cos(1) = " << std::cos(1) << ")\\n";

     std::complex<double> z2(0.0, 1.0); // behaves like real cosh along the imaginary line
     std::cout << "cos" << z2 << " = " << std::cos(z2)
               << " (cosh(1) = " << std::cosh(1) << ")\\n";
 }

.SH Output:

 cos(1.000000,0.000000) = (0.540302,-0.000000) ( cos\fB(1)\fP = 0.540302)
 cos(0.000000,1.000000) = (1.543081,-0.000000) (cosh\fB(1)\fP = 1.543081)

.SH See also

   sin(std::complex)  computes sine of a complex number (\\({\\small\\sin{z}}\\)sin(z))
                      \fI(function template)\fP
   tan(std::complex)  computes tangent of a complex number (\\({\\small\\tan{z}}\\)tan(z))
                      \fI(function template)\fP
   acos(std::complex) computes arc cosine of a complex number
   \fI(C++11)\fP            (\\({\\small\\arccos{z}}\\)arccos(z))
                      \fI(function template)\fP
   cos
   cosf               computes cosine (\\({\\small\\cos{x}}\\)cos(x))
   cosl               \fI(function)\fP
   \fI(C++11)\fP
   \fI(C++11)\fP
   cos(std::valarray) applies the function std::cos to each element of valarray
                      \fI(function template)\fP
   C documentation for
   ccos
